In recent years, in radio communication, particularly in mobile communication, various kinds of information such as images and data as well as speech are subjected to transmission. From now on, it is expected that demands further increase for transmitting various types of content, and it naturally follows that the need for high-speed transmission is expected to further increase. However, when high-speed transmission is performed in mobile communication, the influence of delayed waves due to multipath is not negligible, and transmission performance degrades due to frequency selective fading.
Multicarrier communication such as OFDM (Orthogonal Frequency Division Multiplexing) is focused upon as one of counter techniques of frequency selective fading. Multicarrier communication is a technique of transmitting data using a plurality of carriers (subcarriers) with transmission speed suppressed to such an extent that frequency selective fading does not occur, which results in high-speed transmission. Particularly, the OFDM scheme utilizes a plurality of subcarriers which are orthogonal to each other and where data is arranged, provides high frequency efficiency in multicarrier communication, can be implemented with relatively simple hardware, is particularly focused upon and is variously studied.
Meanwhile, in mobile communication, an adaptive array antenna (hereinafter “AAA”) technique is studied for adaptively controlling reception directivity by multiplying signals received by a plurality of antennas by weighting coefficients (weight). This AAA technique makes it possible to cancel interference signals from received signals by controlling the weight adaptively using MMSE (Minimum Mean Square Error).
Then, for example, Patent Document 1 discloses a technique for estimating an optimum weight promptly and precisely in a receiving apparatus where the OFDM scheme and AAA technique are combined.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-218759